Expressed Sequence Tags (ESTs) are partial nucleotide sequences derived from clones that are randomly-selected from cDNA libraries. The accumulation and analysis of ESTs has become an important component of genome research as well as an important resource for molecular and cellular biology and biotechnology. Nearly four years ago, we created dbEST as a special division of GenBank for cDNA sequence and mapping data. dbEST currently contains 328,905 sequences with the majority (79%) from 50 different human tissues. Data is made available to the public by a variety of means including BLAST searches, the "retrieve" e-mail server, as a World Wide Web - page and by anonymous ftp. There have been nearly 200,000 accessed to date. Of the 45 human disease genes positionally cloned to date, 79% have exact matches in dbEST demonstrating the utility of this resource for gene discovery. Over the past year we have been collaborating with an international consortium to produce a gene-based or "transcript" map of the human genome.